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Biomedical subjects

L A Simons

Publications and source records attributed to L A Simons.

125 records · Page 7Linked to original sources
PubMed1976

Changes in plasma lipoproteins in subjects treated with the bile acid-sequestering resin polidexide (Secholex).

The effects of a new anion-exchange resin, polidexide, 3-30 grams/day, on plasma lipids and lipoproteins have been studied in one normal subject and in three hyperlipidaemic patients. Plasma cholesterol concentrations were significantly reduced in all subjects over 80-120 days of therapy by amounts ranging from 14 to 20%. Plasma triglyceride concentrations increased in two patients with pre-existing hypertriglyceridaemia. Plasma apolipoprotein-B concentrations were reduced in all subjects. Cholesterol and apo-B concentrations in low density lipoproteins were reduced in all subjects, while triglyceride concentrations in very low density lipoproteins were increased in 3/4 subjects; Changes in high density lipoproteins were quite variable.

Adult↗
PubMed1976

Plasma lipoproteins in pregnancy.

Plasma cholesterol, triglyceride and apolipoprotein B were measured in healthy women during pregnancy. Hyperlipidaemia was most marked in the third trimester of pregnancy, but the increases in cholesterol, triglyceride and apolipoprotein-B were not identical (14, 74 and 36%, respectively). The increase in plasma cholesterol was due to a progressive rise in very low density (VLDL) and low density (LDL) lipoproteins. There was a change in composition and size of both VLDL and LDL, demonstrated by a reduction in the ratio of cholesterol to apolipoprotein-B and altered properties of both lipoproteins on polyacrylamide gradient gel electrophoresis. It is difficult to explain these changes but they did not appear to be related to growth hormone, oestrogens or progestogens.

Acromegaly↗
PubMed1975

Cholesterol metabolism in hypertriglyceridaemia and the effects of treatment.

The faecal output of bile acids and endogenous neutral steroids was increased in three hypertriglyceridaemic patients. One patient had familail type IIb, one had type IV and the third had type V hyperlipoproteinaemia. The hyperlipidaemia in the type IV and type V patients was associated with diabetes and a high alcohol intake. The plasma cholesterol and triglyceride concentrations and the faecal output of bile acids decreased significantly when the type IIb patient was given D-thyroxine plus propranolol, and when the type IV and type V patients were treated by withdrawal of alcohol, a low=carbohydrate diet and insulin or glibenclamide. The findings are discussed in relation to the possibility that hypertriglyceridaemia and increased bile acid synthesis in these patients have a common metabolic origin.

Adult↗
PubMed1975

The biochemical composition and metabolism of lipoproteins in type V hyperlipoproteinaemia.

The biochemical composition of lipoproteins in Type V hyperlipoproteinaemia was investigated with special reference to apolipoprotein-B. The in vivo metabolism of protein-labelled low density lipoprotein was also studied in five such patients (3 diabetic, 2 obese subjects). In association with pathologically elevated plasma levels of chylomicrons and very low density lipoproteins, low density lipoprotein concentration was significantly reduced. The proportions of triglyceride to apo-B and triglyceride to cholesterol were significantly increased in all lipoprotein classes, while the proportion of cholesterol to apo-B was significantly reduced. Disappearance of chylomicronaemia with treatment was associated with a prompt increase in low density lipoprotein concentration. The reduced low density lipoprotein concentration was accompanied by an accelerated fractional turnover rate, and by an absolute turnover rate which was subnormal. These results were interpreted as reduced synthesis of low density lipoprotein apoprotein and as a possible block in the conversion of very low density lipoprotein to low density lipoprotein in some Type V patients.

Adolescent↗
PubMed1975

Type V hyperlipoproteinaemia re-visted: findings in a sydney population.

The clinical and biochemical features of eleven patients with Type V hyperlipoproteinaemia have been reviewed. All patients were male, and there was a high incidence in the group of obesity, vascular disease, acute abdominal pain, gout, diabetes mellitus and alcoholism. Plasma cholesterol concentrations ranged from 212 to 1512 mg/100ml and triglycerides from 708 to 7670 mg/100 ml. Lipaemia was associated with significant hyponatraemia, and also interfered with the determination of plasma glucose and serum amylase. Chylomicronaemia and hyperprebetalipoproteinaemia were accompanied by reduction in the pools of beta and alpha lipoproteins. All lipoprotein classes were relatively depleted of cholesterol compared to triglyceride. There was a variable pattern of treatment response. In some patients alcohol withdrawal produced a rapid improvement in plasma lipids. In diabetes mellitus there were two types of response: a rapid one in chronic insulin deficiency, and secondly, a more gradual one in mild diabetes associated with hyperinsulinaemia. In other patients there was a rapid response to carbohydrate-calorie restriction but the respective contributions of each of the steps remained unclear.

Adult↗
PubMed1975

Studies on the nature and causes of hyperlipidaemia in uraemia, maintenance dialysis and renal transplantation.

Fasting serum triglyceride and cholesterol measurements, and lipoprotein characterization by ultracentrifugation, were performed in four groups of patients with chronic renal disease (uraemic, short- and long-term haemodialysis and renal transplant recipients) and the results compared with those obtained from age- and sex-matched control subjects. Basal insulin and growth hormone levels, and serum creatinine and albumin concentrations were measured in, and detailed dietary histories taken from patients in each group. The predominant lipid abnormalities were hypertriglyceridaemia and increased very low density lipoproteins (type IV hyperlipoproteinaemia) in both uraemic and haemodialysis patients. Following renal transplantation, a different pattern of hyperlipidaemia was found. Hypercholesterolaemia was more common and hypertriglyceridaemia less common than in the uraemic and haemodialysis group. The lipoprotein abnormalities were increased low density and/or very low density lipoproteins, with types IIa IIb and IV hyperlipoproteinaemia occurring equally frequently. In uraemic and haemodialysis patients, the proportion of carbohydrate in the diet was high, and may have played a role in the genesis of hypertriglyceridaemia. There was a positive correlation between relative body weight and serum triglyceride in the long-term dialysis group. In renal allograft recipients hypertriglyceridaemia could be attributed, at least in part, to obesity, prednisone dosage and the degree of impairment of graft function. The aetiology of hypercholesterolaemia in the transplant recipients was unclear. Neither basal insulin nor growth hormone levels were elevated in any patient group. Uraemic hypertriglyceridaemia is a clearly defined and well documented metabolic abnormality which is not corrected by dialysis. Post-transplantation hyperlipidaemia however, is a condition of variable presentation and multifactorial aetiology.

Adolescent↗
PubMed1962

SURVIVAL OF BACTERIA AFTER TWENTY-ONE YEARS IN THE DRIED STATE.

Miller, Ruth E. (Woman's Medical College of Pennsylvania, Philadelphia) and Loraine A. Simons. Survival of bacteria after twenty-one years in the dried state. J. Bacteriol. 84:1111-1114. 1962.-Cultures dried in a vacuum over calcium chloride at room temperature and stored in the refrigerator at 10 C were rehydrated after 21 years in this condition. Only 13 of 202 cultures, representing 67 different species, failed to grow. Nine of these were members of four different species, several other strains of which grew on rehydration. Failure to grow may have been due to a small inoculum before drying. Of 32 dried cultures removed from vacuum and stored in the refrigerator exposed to air, 9 survived for periods varying from 37 to 43 weeks. Cultures which survived generally retained the properties they had before drying. In this study, the grampositive organisms survived drying better than gram-negative bacteria. Since the number of organisms in the original inoculum before drying was not determined, quantitative studies could not be done. It is concluded that this procedure is a very satisfactory method for the preservation of even the most delicate organisms for long periods of time.

Journal Article↗
PubMedDate not supplied

Metabolic studies with probucol in hypercholesterolaemia.

Probucol (1 g/day) was administered for 6 months to 16 hypercholesterolaemic patients previously stabilized on diet alone. Total plasma cholesterol fell by 16%, LDL cholesterol by 14% and HDL cholesterol by 41%. The ratio of total cholesterol to HDL cholesterol increased by 40%. Total plasma triglycerides showed a slight upward trend. The extent of the fall in HDL cholesterol was directly proportional to the pre-treatment HDL cholesterol concentration. In 2 patients studied, treatment with Probucol produced a sustained increase in the excretion of endogenous faecal steroids, due to increased faecal bile acids. In 3 patients studied, Probucol increased the degree of cholesterol saturation in gall bladder bile. The Lithogenic Index approximated to pathological levels in 1 patient whose bile was previously relatively saturated with cholesterol. Probucol also appeared to cause a modest reduction in the degree of platelet activation in vivo, with reduced platelet prostaglandin synthesis and reduced release of platelet peptides.

Adult↗
PubMedDate not supplied

The fate of the orally administered bile acid sequestrant, polidexide, in humans.

1. The metabolic fate of the insoluble bile acid sequestrant polidexide, (poly-[2-(diethylamino)ethyl] polyglycerylenedextran hydrochloride), was studied in four adult humans following the oral administration of the 14C-labelled substance. 2. The mean cumulative recovery of 14C in faeces was 95-3% (s.e.m. = 1-1) of the administered dose, while mean cumulative recovery in urine was 0-37% (s.e.m. = 0-13) of the oral dose. 3. Only background levels of radioactivity were detectable in plasma samples taken 1-3 days after administration of tracer. 4. The findings suggested that polidexide was not absorbed from the gastrointestinal in man to any significant degree.

Adult↗
PubMedDate not supplied

The effect of metoprolol and atenolol on plasma high density lipoprotein levels in man.

1. The effects of two beta-adrenoreceptor blocking drugs, metoprolol and atenolol, on plasma lipoproteins were studied in thirty-four patients using a single-blind cross-over design, with a 10-day placebo washout period between drugs. 2. Compared with placebo values, neither metoprolol nor atenolol influenced total plasma cholesterol levels, while total plasma triglycerides increased slightly. 3. Low density lipoprotein protein level remained unaltered, while high density lipoprotein (HDL) cholesterol and protein were significantly reduced by both beta-adrenoreceptor blockers. 4. The ratio of total cholesterol to HDL cholesterol was increased by both drugs. 5. The data suggest that patients taking these drugs over many years may be exposing themselves to increased vascular risk, despite other anticipated benefits from such therapy.

Atenolol↗